Partial Kammback

Weather Spotter's partial Kammback

Introduction
One of the biggest aerodynamic problems with the majority of bluff body vehicles (most hatchbacks, vans, wagons) is the amount of pressure drag / size of the trailing wake. In other words, the rear of the vehicle is where the big gains are to be made.

That said, a hatchback configuration isn't automatically an aerodynamic death sentence. Several of the most slippery production cars in recent years (1st gen Insight, 2nd gen Prius, Audi A2) have used "Kammback" shapes, where the roofline tapers downward, following a particular shape (a "chopped" teardrop).

It's possible to retrofit this shape onto existing vehicles and gain a measurable improvement in fuel economy.

Instructions for mod

Information required: How do people perform this modification, pictures, problems, what to look out for
Information required: A listing for different ways to do this if its different on different types of cars

User experiences

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User data
User Name	Car Make, Model, Year	Cost of Mod	Time to Perform Mod	MPG Before Mod	MPG After Mod	MPG improvement guess	Instruction Link
Weather Spotter	Toyota, Matrix, 2006	$15 USD	12 hr	45.06	45.98	1.98% (.91 MPG) ABA testing 2.34% better aero (coast down testing)	Weather Spotter's Data and How To
3dplane	94 Mazda Protege DX	$34	8 hr			limited testing showed that the particular design hurt MPG	3dplane's Kammback how to
wyatt	94 Suzuki Swift 5MT	$10	12 hr	48	50.9	6% (2 1800+ mile trips) 12% better aero (coast down testing)

Problems / Consequences of mod

You might reduce your rear view, most states require a certain distance behind your car to be viewable. You also might add to the length of you car (parking issues).